rework and document api
This commit is contained in:
Kevin Jahns
273
src/utils/RelativePosition.js
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273
src/utils/RelativePosition.js
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import {
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getItem,
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getItemType,
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createID,
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writeID,
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readID,
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compareIDs,
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getState,
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findRootTypeKey,
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AbstractItem,
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ItemType,
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ID, StructStore, Doc, AbstractType // eslint-disable-line
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} from '../internals.js'
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import * as encoding from 'lib0/encoding.js'
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import * as decoding from 'lib0/decoding.js'
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import * as error from 'lib0/error.js'
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/**
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* A relative position is based on the Yjs model and is not affected by document changes.
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* E.g. If you place a relative position before a certain character, it will always point to this character.
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* If you place a relative position at the end of a type, it will always point to the end of the type.
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*
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* A numeric position is often unsuited for user selections, because it does not change when content is inserted
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* before or after.
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*
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* ```Insert(0, 'x')('a|bc') = 'xa|bc'``` Where | is the relative position.
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*
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* One of the properties must be defined.
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*
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* @example
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* // Current cursor position is at position 10
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* const relativePosition = createRelativePositionFromIndex(yText, 10)
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* // modify yText
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* yText.insert(0, 'abc')
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* yText.delete(3, 10)
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* // Compute the cursor position
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* const absolutePosition = createAbsolutePositionFromRelativePosition(y, relativePosition)
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* absolutePosition.type === yText // => true
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* console.log('cursor location is ' + absolutePosition.index) // => cursor location is 3
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*
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*/
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export class RelativePosition {
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/**
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* @param {ID|null} type
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* @param {string|null} tname
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* @param {ID|null} item
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*/
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constructor (type, tname, item) {
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/**
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* @type {ID|null}
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*/
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this.type = type
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/**
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* @type {string|null}
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*/
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this.tname = tname
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/**
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* @type {ID | null}
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*/
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this.item = item
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}
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}
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/**
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* @param {Object} json
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* @return {RelativePosition}
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*
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* @function
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*/
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export const createRelativePositionFromJSON = json => new RelativePosition(json.type == null ? null : createID(json.type.client, json.type.clock), json.tname || null, json.item == null ? null : createID(json.item.client, json.item.clock))
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export class AbsolutePosition {
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/**
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* @param {AbstractType<any>} type
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* @param {number} index
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*/
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constructor (type, index) {
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/**
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* @type {AbstractType<any>}
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*/
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this.type = type
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/**
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* @type {number}
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*/
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this.index = index
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}
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}
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/**
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* @param {AbstractType<any>} type
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* @param {number} index
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*
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* @function
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*/
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export const createAbsolutePosition = (type, index) => new AbsolutePosition(type, index)
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/**
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* @param {AbstractType<any>} type
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* @param {ID|null} item
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*
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* @function
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*/
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export const createRelativePosition = (type, item) => {
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let typeid = null
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let tname = null
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if (type._item === null) {
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tname = findRootTypeKey(type)
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} else {
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typeid = type._item.id
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}
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return new RelativePosition(typeid, tname, item)
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}
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/**
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* Create a relativePosition based on a absolute position.
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*
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* @param {AbstractType<any>} type The base type (e.g. YText or YArray).
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* @param {number} index The absolute position.
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* @return {RelativePosition}
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*
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* @function
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*/
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export const createRelativePositionFromTypeIndex = (type, index) => {
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let t = type._start
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while (t !== null) {
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if (!t.deleted && t.countable) {
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if (t.length > index) {
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// case 1: found position somewhere in the linked list
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return createRelativePosition(type, createID(t.id.client, t.id.clock + index))
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}
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index -= t.length
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}
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t = t.right
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}
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return createRelativePosition(type, null)
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}
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/**
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* @param {encoding.Encoder} encoder
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* @param {RelativePosition} rpos
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*
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* @function
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*/
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export const writeRelativePosition = (encoder, rpos) => {
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const { type, tname, item } = rpos
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if (item !== null) {
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encoding.writeVarUint(encoder, 0)
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writeID(encoder, item)
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} else if (tname !== null) {
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// case 2: found position at the end of the list and type is stored in y.share
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encoding.writeUint8(encoder, 1)
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encoding.writeVarString(encoder, tname)
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} else if (type !== null) {
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// case 3: found position at the end of the list and type is attached to an item
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encoding.writeUint8(encoder, 2)
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writeID(encoder, type)
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} else {
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throw error.unexpectedCase()
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}
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return encoder
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}
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/**
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* @param {RelativePosition} rpos
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* @return {Uint8Array}
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*/
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export const encodeRelativePosition = rpos => {
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const encoder = encoding.createEncoder()
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writeRelativePosition(encoder, rpos)
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return encoding.toUint8Array(encoder)
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}
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/**
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* @param {decoding.Decoder} decoder
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* @return {RelativePosition|null}
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*
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* @function
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*/
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export const readRelativePosition = decoder => {
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let type = null
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let tname = null
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let itemID = null
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switch (decoding.readVarUint(decoder)) {
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case 0:
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// case 1: found position somewhere in the linked list
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itemID = readID(decoder)
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break
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case 1:
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// case 2: found position at the end of the list and type is stored in y.share
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tname = decoding.readVarString(decoder)
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break
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case 2: {
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// case 3: found position at the end of the list and type is attached to an item
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type = readID(decoder)
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}
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}
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return new RelativePosition(type, tname, itemID)
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}
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/**
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* @param {Uint8Array} uint8Array
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* @return {RelativePosition|null}
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*/
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export const decodeRelativePosition = uint8Array => readRelativePosition(decoding.createDecoder(uint8Array))
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/**
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* @param {RelativePosition} rpos
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* @param {Doc} doc
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* @return {AbsolutePosition|null}
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*
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* @function
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*/
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export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
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const store = doc.store
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const rightID = rpos.item
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const typeID = rpos.type
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const tname = rpos.tname
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let type = null
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let index = 0
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if (rightID !== null) {
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if (getState(store, rightID.client) <= rightID.clock) {
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return null
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}
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const right = getItem(store, rightID)
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if (!(right instanceof AbstractItem)) {
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return null
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}
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index = right.deleted || !right.countable ? 0 : rightID.clock - right.id.clock
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let n = right.left
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while (n !== null) {
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if (!n.deleted && n.countable) {
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index += n.length
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}
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n = n.left
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}
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type = right.parent
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} else {
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if (tname !== null) {
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type = doc.get(tname)
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} else if (typeID !== null) {
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if (getState(store, typeID.client) <= typeID.clock) {
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// type does not exist yet
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return null
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}
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const struct = getItemType(store, typeID)
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if (struct instanceof ItemType) {
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type = struct.type
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} else {
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// struct is garbage collected
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return null
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}
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} else {
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throw error.unexpectedCase()
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}
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index = type._length
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}
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if (type._item !== null && type._item.deleted) {
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return null
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}
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return createAbsolutePosition(type, index)
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}
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/**
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* @param {RelativePosition|null} a
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* @param {RelativePosition|null} b
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*
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* @function
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*/
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export const compareRelativePositions = (a, b) => a === b || (
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a !== null && b !== null && a.tname === b.tname && compareIDs(a.item, b.item) && compareIDs(a.type, b.type)
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)
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